In the times that I have attended the Soorp Badarak at an Armenian Apostolic parish, the priest will step down to where the people are and give Holy Communion standing. I have also attended liturgies when a Catholicos was the celebrant and have seen the same thing.I can understand if it is a matter of problems with the knees, but I was wondering if this practice is still generally done or if it is becoming less common, even among younger priests.

I have attended the Soorp Badarak at Armenian Catholic parishes, but because the sanctuary is not elevated as one generally finds in an Armenian Apostolic parish the priest gives Holy Communion standing.

From what I understand, it's purely a matter of logistics. Some churches have pretty low bemas, and in those churches it's not a problem to administer from the bema while standing. In churches where the bema is really high, it would be difficult for the priest in a standing position to safely reach down low enough to put the communion in the mouth of the communicant. It's just easier to kneel where the bema is really high.